In recent years, liquid crystal displays are often used as flat panel displays in various fields. However, the following problems still remain. Contrast and tinge greatly vary depending on viewing angles. A need for a light source such as a backlight hinders lower power consumption. Reduction in the thickness and weight of a liquid crystal device is limited. Liquid crystal display devices have serious problems also in flexibility.
To address the problems, self-luminous organic EL display devices including organic EL elements are expected in place of liquid crystal display devices. In an organic EL element, a current flows through organic EL layers sandwiched between an anode and a cathode so that organic molecules forming the organic EL layers emit light. Organic EL display devices including such an organic EL element, which are self-luminous, have their thickness and weight easily reduced, and consume less power. The organic EL display devices, which have a wide viewing angle, receive great attention as flat panels that have an advantage over liquid crystal panels.
Flexible organic EL display devices including a plastic substrate draw special attention. The plastic substrate has higher flexibility, higher shock resistance, and lower weight than a glass substrate. Such a plastic substrate would provide new organic EL display devices beyond typical displays including a glass substrate.
Here, such a flexible organic EL display device, which has a pliant structure, warps due to vibrations and other factors. As a result, an intended luminous intensity may be unable to be obtained, or an organic EL element may be broken.
To avoid these inconveniences, an organic EL display device including a protective plate to improve the mechanical strength of the device has been proposed. More specifically, at least one of upper and lower surfaces of such an organic EL display device is provided with a protective plate (a support plate) made of resin, rubber, or any other suitable material. Such a configuration may increase the mechanical strength of a bent portion (see, for example, Patent Document 1).